Apparatus and methods for filtering metals

ABSTRACT

An apparatus and method for filtering molten metal (M), such as aluminum or an aluminum alloy includes at least one ceramic foam filter or any other type of filtration media such as porous tube or alumina balls disposed in a receptacle ( 12 ) for the molten metal (M). A vibrator vibrates at least one of the filter, the receptacle ( 12 ) or the metal and may be used to induce priming, filtering and/or drainage of the filter. The vibrator may be retrofitted to an existing filter system and may be adjustable in frequency and amplitude. The vibration may be continuous over a given period or produced in a single shock.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/607,062, filed May 26, 2017, which claims the benefit of U.S.Provisional Application No. 62/343,489, filed May 31, 2016, entitled,Apparatus and Methods For Filtering Metals, each of which isincorporated by reference herein in its entirety.

FIELD

The present invention relates to the filtration of aluminum metal in amolten state, and more particularly, to filtration by porous filters,such as ceramic filters.

BACKGROUND

Ceramic filters, e.g., ceramic foam filters (CCFs) are known for use infiltering or removing contaminants from molten metal, e.g., aluminummetal and alloys. The use of such filters has associated limitations andchallenges, such as, starting a flow of molten metal through the filterby displacing air in the internal pores/passageways in the filter(priming). Known methods for accomplishing this task include pre-heatingthe filter, establishing a sufficient head of molten metal above thefilter to exert pressure to push the molten metal through the filter,applying a negative pressure on the downstream side of the filter byapplying a vacuum on the downstream side, and agitating/driving themolten metal against and through the filter with an electromagneticfield which has a hydrodynamic effect on the molten metal.Notwithstanding, these known methods, alternative methods and apparatusfor facilitating metal flow through a filter remain desirable.

SUMMARY

The disclosed subject matter relates to a filter device having areceptacle for molten metal, the receptacle having an inlet throughwhich the metal may enter the receptacle and an outlet through which themetal may exit the receptacle; a filter element within the receptaclepositioned between the inlet and the outlet, the filter capable ofpassing molten metal there through; and a vibrator capable of inducingvibrations in the metal.

In another embodiment, the vibrator contacts a surface of thereceptacle.

In another embodiment, the vibrator has a driven element that contactsthe metal.

In another embodiment, the driven element is immersed in the metal.

In another embodiment, the device has an arm extending between thevibrator and the driven element.

In another embodiment, the arm is L-shaped.

In another embodiment, further including a support for the receptacleand wherein the arm is attached to the support.

In another embodiment, further including at least one resilient elementinterposed between the arm and the support enabling the arm to vibrateunder the influence of the vibrator at least partially independently ofthe support.

In another embodiment, the vibrator is at least one of electrically,pneumatically or hydraulically driven.

In another embodiment, the vibrator generates a force with a directionbetween 45° to 90° relative to the direction of metal flow.

In another embodiment, the vibrator is mounted on an exterior surface ofthe receptacle proximate the filter element.

In another embodiment, further including a controller for the vibrator,the controller capable of adjusting the vibrator in at least one offrequency and amplitude.

In another embodiment, the receptacle has an inner liner that receivesthe metal and an outer shell.

In another embodiment, further including at least one resilient memberinterposed between the inner liner and the outer shell.

In another embodiment, the at least one resilient member at leastpartially isolates the vibration of the inner liner from the shell.

In another embodiment, the filter is a ceramic foam filter.

In another embodiment, the filter has >50 pores per inch.

In another embodiment, the filter has ≥60 pores per inch.

In another embodiment, the filter could be a bed filter, a porous tubeor any known filtration media for molten metal.

In another embodiment, the molten metal includes aluminum.

In another embodiment, the driven element is at least partially coveredby a refractory material.

In another embodiment, further including at least one additionalvibrator, the vibrator and additional vibrator operable independently orsimultaneously and at the same frequency or different frequencies.

In another embodiment, a method of priming a filter with pores forfiltering molten metal, the filter disposed in a reservoir, includes thesteps of pouring the molten metal into the reservoir onto the filter;and vibrating at least one of the molten metal, the filter or thereservoir to induce passage of the molten metal into pores of thefilter, displacing air residing in the filter.

In another embodiment, a method of draining a filter with porescontaining molten metal, includes the steps of: vibrating the filtercontaining the molten metal, inducing the metal in the pores of thefilter to flow out.

In another embodiment, further including the step of draining the filterof molten metal and during at least part of the step of draining,simultaneously vibrating at least one of the molten metal, the filter orthe reservoir inducing the metal in the pores of the filter to flow out.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, referenceis made to the following detailed description of exemplary embodimentsconsidered in conjunction with the accompanying drawings.

FIG. 1 is a perspective view of filtering device in accordance with anembodiment of the present disclosure.

FIG. 2 is a plan view of the device of FIG. 1.

FIG. 3 is a partial cross-section of the device of FIGS. 1 and 2, takenalong section line 2-2 and looking in the direction of the arrows.

FIG. 4 is a diagrammatic view of a filtering device in accordance withan alternative embodiment of the present disclosure.

FIG. 5 is a diagrammatic view of a filtering device in accordance withanother alternative embodiment of the present disclosure.

FIG. 6 is a diagrammatic view of a filtering device in accordance withanother alternative embodiment of the present disclosure.

FIG. 7 is a diagrammatic view of a filtering device in accordance withanother alternative embodiment of the present disclosure.

FIG. 8 is a diagrammatic view of a filtering device in accordance withanother alternative embodiment of the present disclosure.

FIG. 9 is a diagrammatic view of a filtering device in accordance withanother alternative embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

In the processing of metals, it may be preferable to remove certaincontaminants and inclusions. For example, in the case of aluminum andaluminum alloys, it may be desirable to remove oxides of aluminum andmagnesium, borides, carbides, nitrides and spinels to promote a morepure metal product for various reasons. This contaminant removal hasbeen performed by porous ceramic filters, e.g., ceramic foam filters(CFFs) through which a stream of molten metal is passed. As with filtersgenerally, the smaller the pore size and the greater the thickness ofthe filter, the more effective the filtration process is in removingcontaminants, but the more restrictive the filter is to flow. As appliedto filtering liquid metal, ceramic filters exhibit a requirement to beprimed, i.e., to initiate flow through the filter by displacing airpresent in the pores of the filter by liquid metal. Approaches forfacilitating metal flow through ceramic filters include pre-heating thefilter so the initial flow of metal is not solidified upon contactingthe filter and creating a sufficient height (head) of molten metal abovethe filter to push the metal through the filter. Typically, there arelimitations on the head of metal that may be established in a givenmetal handling facility, so alternative methods and apparatus have beenused. For example, a low pressure may be established on the downstreamside of the filter by vacuum apparatus, as disclosed, e.g., in U.S. Pat.No. 7,666,248, which is incorporated by reference herein in itsentirety. In another approach, an induction coil may be used to produceLorentz forces that act on the metal and facilitate a flow of metalthrough the filter as disclosed in Canadian Patent Document No. CA2,871,245, which is incorporated by reference herein in its entirety.

The present disclosure recognizes that vibratory mechanisms may also beused to facilitate passage of molten metal through a filter. Moreparticularly, mechanical, electrical, electro-mechanical, air poweredand/or hydraulic powered mechanisms may be utilized to establish avibration of the filter, the container/receptacle through which themolten metal passes in proximity to the filter and/or the molten metal,to facilitate metal flow through the filter. The vibration may be in thenature of a wave, e.g., a compression/pressure wave, like an acousticwave, in one embodiment, at an ultrasonic frequency, that is transmittedthrough the metal from a transducer/vibrator acting on the filter, thereceptacle/conduit in communication with or proximate to the filter, orthe molten metal. The use of a vibratory mechanism for this purpose maypermit the passage of molten metal through filters that are finer thanthat which would normally be used. For example, in many traditionalmetal purification systems, filters finer than 50 pores per inch (PPI)are not useable. In accordance with the present disclosure, filtersfiner than 50 PPI or finer may be used, e.g., a filter of 50 PPI to 80PPI.

A vibratory mechanism/technique of filtration in accordance with thepresent disclosure may be used to facilitate priming at the beginning ofthe cast to use the full surface of the filter, during filtration and/orafter filtration of a batch of molten metal is concluded, e.g., topromote the removal of metal and/or trapped contaminants from thefilter. In this later application, the removal of metal and contaminantsfrom the filter may extend the useful life of the filter, e.g., for abed filter, this technique may be used to extend the life and flushinclusions to continue with a refreshed bed. It may also reduce theamount of heating that would otherwise be needed for reestablishing aflow of molten metal through the filter in a subsequent filtration run.It should be appreciated that the vibratory mechanisms and methods ofthe present disclosure may be used independently of the known methodsand apparatus used to prime filters and promote metal flow therethrough. Alternatively, the vibratory approach of the present disclosuremay be used in conjunction with known methods. For example a vibratoryapparatus may be used independently of or in conjunction with vacuum ormagnetic induction assist type of filtration promoter.

FIGS. 1-3 show a filtering device 10 in accordance with an embodiment ofthe present disclosure, which has a receptacle 12 for molten metal Mthat is directed into the interior cavity 12C thereof. In the embodimentshown, the receptacle has four tapering walls 12W forming a funnelshape. The receptacle 12 is held to a supporting framework 14 by amounting plate 12P attached to the receptacle 12 and clamped by clamps16, e.g., in the form of Vise Grip wrenches fastened to support beams14B of the framework 14. Alternatively, the receptacle could be fastenedto the framework 14 by bolts or other types of fasteners. The framework14 has wheels 18 permitting movement of the device 10 by rolling. Theframework 14 has a lower portion 14L which supports the receptacle 12and a vertical support 14V with a plate 20 having a slot 20S. A vibratorassembly 22 features a vibrator 24 attached to an arm 26 with a drivenplate 28 attached at one end. There are a large number of differenttypes of vibrators that could be employed, such as those driven by air,hydraulics or electrical power. These types of industrial vibrators maybe obtained commercially, e.g., from VIBCO of Wyoming, R.I., U.S.A. Inone example, a VIBCO model no. SCR-100 provides about 1825 impacts perminutes producing 2105 pounds of force per impact for an operating airpressure of 60 to 80 psi. In another example, the vibrator may be ajackhammer drill, such as a commercial jackhammer drill from Dewalt,producing vibrations at a frequency of 1500 impacts per minute at amagnitude of 2000 pounds per impact. In yet another example, an airdriven vibrator, such as, a Martin P-Series P4S pneumatic pistonvibrator from Martin Engineering of Neponset, Ill., www.martin-eng.commay be used. In this example, air pressure is converted to vibrationfrequency and force magnitude.

In the embodiment shown, the arm 26 has a horizontally extending portion26H providing a selected relative horizontal position of the vibratorassembly 22 relative to the receptacle 12, e.g., allowing the drivenplate 28 to be centered in the receptacle 12 and a vertically extendingportion 26V permitting the driven plate 28 to be extended down into thereceptacle 12 to a selected height. As shown in FIG. 3, the horizontallyextending portion 26H is attached at one end to a mounting plate 30 towhich one or more resilient mounting assemblies 32 (e.g., elastomeric orspring mountings) attach. The resilient mounting assemblies 32 have aresilient element 32R and a shaft 32S that attaches at one end tomounting plate 30, extend through resilient element 32R, through slot20S and pivotally attach to a handle portion 32H with cam elements 32C.This type of handle 32H may be obtained commercially, e.g., fromMcMaster Carr of Elmhurst, Ill., U.S.A. When in the gripping position(with the handle portion 32H pressed down) the mounting assemblies 32grip the plate 20 at a given, adjustable position, such that thevibrator assembly 22 may be positioned at a selected height relative tothe receptacle 12 and relative to the height (head) H of molten metal Mtherein. The resilient elements 32R provide freedom of motion andisolate vibrational movement induced by the vibrator 24 from thesupporting framework 14. The vibration induced by the vibrator 24 istransmitted along the arm 26 to the driven plate 28 and to the moltenmetal M, which is poured into the receptacle 12, e.g., to a height (headlevel) H, as shown diagrammatically in dotted lines. As can beappreciated, when molten metal is flowing through the device 10, thehead level H may vary dynamically as determined by variations in inflowand outflow. The driven plate 28 may be positioned at any given depthwithin the molten metal, ranging from surface contact at the top surfaceof the molten metal M metal to a depth therein approaching the bottom ofthe receptacle 12.

As shown in FIG. 3, the receptacle 12 has a metal shell 12S, e.g., madefrom steel, and a refractory liner 12R, e.g., made from ceramic, e.g.,N-14-N-17, as referred to at the website pyrotek-inc.com, alumina or anyrefractory material used for trough construction for molten aluminum orother metals. The refractory liner 12R may be a coating applied to theshell 12S or may be made as a separate insert that is inserted into theshell 12S after independent formation. A filter 34, e.g., made fromceramic foam (CCF) is positioned at the bottom of the receptacle 12through which molten metal M poured into the receptacle 12 may pass toremove inclusions and contaminants. The filter may be of a type obtainedcommercially, such as a CCF filter from 30 PPI to 80 PPI from Selee(selee.com). In one example, the molten metal may be aluminum or analuminum alloy. The filter 34 is contained within a filter housing 36having an outer metal shell 36S, e.g., of steel, and an internalrefractory lining 36R. The refractory lining 36R may be tapered inwardlyin the discharge direction to receive a filter 34 with a complementarytaper, allowing the filter 34 to be placed and held within the filterhousing 36 without the filter 34 passing through. The filter housing 36may be provided with a flange 36F that permits clamping to flange 12F onthe receptacle 12 by a clamping mechanism(s), such as clamp devices 16.In this manner, the device 10, may be assembled and disassembled forinspection and maintenance.

In operation, the vibrator assembly 22 may be positioned at a selectedheight before or after molten metal M is directed into the receptacle 12and secured in that position by clamp assembly 32. As shown in FIG. 3,in one approach, the vibrator assembly 22 may be positioned such thatthe driven plate 28 is below the surface of the metal M as shown bydotted line labeled H and diagrammatic view of the driven plate 28 shownin dotted lines. As noted above, the driven plate 28 may be positionedat the top surface (at line H) of the molten metal M. Upon actuation,the vibrator 24 induces vibration in the driven plate 28 with componentsof motion in the up and down direction, as shown by the up and downarrows. The vibration of the driven plate 28 generatescompression/tension waves W in the molten metal M. The waves W progressin a downward direction through the metal M toward the filter 34,inducing the movement of molten metal M through the filter 34. Inaddition to the waves W, waves are also generated with components in aside-to-side direction, as indicated by the double-ended arrow S in FIG.3, such that the waves impinge upon the receptacle 12, setting it intomotion. In addition to moving the molten metal M, the waves Wtransmitted through the metal M impinge upon the housing 12 and thefilter 34 inducing responsive motion thereof in a variety of directions.The relative magnitude of wave propagation in any given direction willdepend upon the vibrator 24, the materials and fabrication techniquesused in making the arm 24 and many other factors. For example, avibrator 24 that uses a spinning mass with eccentric mass distributionwill generate a rounded wave pattern, while a vibrator 24 with alinearly oscillating mass would produce waves with more linearcomponents.

The above described device 10 may be used to induce priming of a filter34 at the beginning of a run or to induce clearance of metal and/ordebris from a filter 34 at the end of a run. The vibrator 24 may beoperated continuously during a run to increase the flow rate of moltenmetal M. In one embodiment, the frequency of vibration and/or themagnitude of the vibrations is adjustable by a controller 38 (FIG. 1),such as a digital electronic controller or an analog device, such as arheostat for an electronic vibrator or a valve for an air or hydraulicvibrator, to accommodate the requirements of a specific operation, e.g.,priming, cleaning of a filter, or to accommodate other variableparameters encountered in a filtering operation. For example, thefrequency and amplitude of vibration may be increased as the filter 34becomes more clogged by debris during the course of filtration. Optimalvibration parameters may be noted and used for various metals andalloys, as well as for varying degrees of contamination and fordifferent types of contaminants in the metal M. The driven plate 28 mayhave dimensions permitting an adequate flow of molten metal M betweenthe outer periphery thereof and the refractory liner 12R of thereceptacle 12 when positioned at a selected degree of insertion into thereceptacle 12. In one alternative, the driven plate 28 and/or portionsof the vertical portion 26V of the arm 26 may be coated with refractorymaterial to make them more resistant to heat and to prevent unwantedheat transfer from the metal M to the vibrator assembly 22. Analternative mounting location is shown in dotted lines for vibrator 24′,viz., on side wall 12S proximate filter 34. As shown, the vibrator 24′is oriented at an angle A relative to a horizontal reference line H. Aforce vector F emanating from the vibrator 24′ is at an angle A, e.g.,45° relative to reference line H. Force vector F bisects the right anglebetween reference line H and the vertically oriented direction of metalflow and therefore is also disposed at 45° relative to the direction ofmetal flow. Other mounting positions and orientations may be utilized.

FIG. 4 shows a filtering device 110 in accordance with anotherembodiment of the present disclosure and having a receptacle 112 with anouter shell 112S, e.g., of steel and a refractory liner 112R. A filter134, such as a ceramic filter (CCF) is positioned within the refractoryliner 112R to filter molten metal (not shown) that passes there through.One or more resilient elements 140A, 140B, 140C, such as springs, areinterposed between the refractory liner 112R and the shell 112S,permitting the refractory liner 112R to move independently of the shell112S. One or more vibrators 124A, 124B, 124C of a type as describedabove are assembled to the shell 112S, such that upon operation, thevibrators 124A, 124B, 124C induce vibrations in/of the shell 112S of aselected frequency and amplitude. In one alternative embodiment, thevibrations are conducted through the resilient elements 140A, 140B, 140Cto the refractory liner 112R. The resilient elements 140A-140C arediagrammatically depicted as springs, but could be elastomeric members.In another embodiment, the vibrators are mechanically coupled to therefractory liner 112R, such that they directly impart vibrations to therefractory liner 112R, which is suspended in the shell 112S by theresilient elements 140A, 140B, 140C. Link L extending between vibrator124A and refractory liner diagrammatically illustrates a mechanicalconnection. The resilient elements 140A, 140B, 140C allow the refractoryliner 112R to move (vibrate) independently of the shell 112S andindependently of structures that the shell 112S is supported by orcoupled to. The vibrators 124A, 124B, 124C may be of the same type andset to deliver vibrations of the same frequency and magnitude or theymay be of different types and may be set to deliver vibrations indifferent frequencies and magnitudes. The vibrators 124A, 124B, 124C maybe supplied by a common energy source, such as a common pressurized airline or electrical supply line or be energized by separate sources,which may be of the same type or of different types, e.g., electricaland pressurized air. The vibrators 124A, 124B, 124C may be operatedsimultaneously, in subsets or individually, in sequence, as fitting forthe stage of operation of the filter device 110, e.g., priming,filtering or draining.

FIG. 5 shows a filtering device 210 in accordance with anotherembodiment of the present disclosure and having a receptacle 212 with anouter shell 212S, e.g., of steel and a refractory liner 212R. A filter234, such as a ceramic filter (CCF) is positioned within the refractoryliner 212R to filter molten metal (not shown) that passes there through.One or more vibrators 224A, 224B, 224C, of a type as described above,are assembled to the shell 212S such that upon operation, the vibrators224A, 224B, 224C induce vibrations in/of the shell 212S of a selectedfrequency and amplitude. Since the shell 212S is in contact withrefractory liner 212R, and the filter 234 is in contact with therefractory liner 212R, the vibrations are conducted to the refractoryliner 212R and filter 234. In addition, when the receptacle 212 containsmolten metal (not shown), the vibration of the refractory liner 212R andthe filter 234 will also be imparted to the molten metal. It should beappreciated that vibrators 24, 124A-C and 224A-C may be adjustable infrequency and amplitude, such that the vibrator(s) may be adjusted tohave maximum efficacy in light of the specific parameters of thecomponents that they set in motion, e.g., the mass, density,flexibility, etc. of the shells 12, 112, 212, the refractory liners 12R,112R, 212R and the metals that are contained therein.

FIG. 5 also shows that the line of vibratory force V may be directed atany given angle A, B, etc. relative to a reference orientation R. In theinstance shown, the reference orientation R is parallel to the wall ofthe shell 212S and perpendicular to the filter 234, with angle A beingabout 90°. As shown by angle B, the vibrator 224A could berepositioned/mounted to generate a vibratory force along dotted line V′,which is at an angle of about 45° relative to the reference orientationR. Given that the vibrators 24, 124, 224A-224C can be installed on anygiven surface if the filtering device 10, 110, 210, a vibratory force Vmay be directed at any angle relative to a given reference orientation.As shall be described below, a force V directed at 45° relative to metalflow through the filter 34, 134, 234 provides good results in filterdevices 10, 110, 210 tested. Other reference orientations and force Vangles may be selected based upon the shape of the filter device andother factors.

It should further be appreciated that while embodiments using arefractory liner, e.g., 12R have been described above, receptacles madefrom heat resistant metals, such as steel or cast iron could also beused without a refractory liner for forming a receptacle that receivesmolten metal and conducts it through a ceramic filter contained therein.

FIG. 6 shows a filtering device 310 having a receptacle 312 that may ormay not utilize an outer shell and a refractory liner. In the embodimentshown, the filtering device 310 utilizes only a refractory element 312R.A pair of spaced filters 334A and 334B bridging a hollow defined by therefractory liner 312R are positioned to sequentially filter molten metalM, which flows through the device 310, as indicated by the arrows. Avibrator 324A is attached to the refractory element 312R and inducesvibrations therein, in the filters 334A and 334B, and in the metal M, tofacilitate flow through the filters 334A and 334B and the device 310.The filters 334A and 334B may be of the same thickness and porosity orof different thickness and or porosity. In one embodiment, the filter334A has a courser porosity, e.g., 50 PPI than filter 334B, e.g., 60PPI. Optionally, a vibrator 324B, like vibrator 24A of FIG. 1 may beused in substitution or in conjunction with vibrator 324A.

FIG. 7 shows a filtering device 410 having a receptacle 412 into which afiltration structure 450 has been installed. The receptacle 412 may bein the form of a tank or channel of refractory material, such asN-14-N-17 or any other industrial material used to contain molten metal,that conducts molten metal M by gravity as it flows from one filter toanother. The filtration structure 450 interrupts the flow of moltenmetal M, dividing the receptacle 412 into three chambers 412C1(upstream), 412C2 (intermediate) and 412C3 (downstream). A pair offilters 434A, and 434B are sealingly received in passageways 450A, 450B,respectively, to filter molten metal M as is flows through the chambers412C1, 412C2 and 412C3, sequentially filtering molten metal M whichflows through the device 410. In one embodiment, a vibrator 424A witharm 426VA and driven plate 428A acts upon the molten metal in chamber412C1 to induce vibrations in the metal M, the receptacle 412, thefilter 434A and the filtration structure 450 to increase metal flowthrough the filter 434A and the device 410. The vibrations induced byvibrator 424A may be sufficient to facilitate flow through filter 434B.In the alternative, a vibrator 424B acting on the receptacle 412 and/ora vibrator 424C may be used sequentially or simultaneously to improveflow through filters 434A, 434B and the device 410. The filters 434A,434B may be of the same thickness and porosity or of different thicknessand or porosity. In one embodiment, the filter 434A has larger pores,e.g., 50 PPI than filter 434B, e.g., 60 PPI, such that filter 434Aconducts a first level of filtration of larger particles and filter 434Bconducts a second level of filtration of smaller particles carried inthe metal M.

FIG. 8 shows a filtering device 510 having two receptacles 512A, 512B,each of which has a filter 534A and 534B therein, respectively andjoined at a junction 512J. In another alternative, the receptacles 512A,512B could be integrated into a continuous trough or channel throughwhich molten metal M flows. The receptacles 512A, 512B may be in theform of tanks or channels of refractory material, such as N-14-N-17 oranother type used in molten metal industries, that conducts molten metalM by gravity as it flows from filter to filter. The filters 534A, and534B are sealingly received in receptacles 512A, 512B, respectively, tofilter molten metal M as is flows there through, sequentially filteringmolten metal M which flows through the device 510. Vibrators 524A, 524Bact upon the receptacles 512A, 512B, the filters 534A, 534B, and themetal M contained therein to increase metal flow through the filters534A, 534B and the device 510. In the alternative, one or more vibrators524C, like vibrators 424A and 424B may be used to act directly on themetal M in receptacles 512A, 512B to improve flow through filters 534A,534B and the device 510. The filters 534A, 534B may be of the samethickness and porosity or of different thickness and or porosity.

FIG. 9 shows a filtering device 610 having two receptacles 612A, 612B,each of which has a ceramic filter 634A and 634B therein, respectively.The receptacles 612A, 612B are supplied with a flow of molten metal M bya conduit 660 that splits in parallel paths 660A, 660B. After passingthrough the receptacles 612A, 612B and filters 634A and 634B, a pair ofconduit paths 660C and 660D rejoin in rejoined conduit 660R to pass themetal M on for a next stage of processing. In one alternative, theconduits 660, 660A, etc., may be channels or troughs made from arefractory material. The filters 634A, and 634B are sealingly receivedin receptacles 612A, 612B, respectively, to filter molten metal M as isflows there through. Vibrators 624A, 624B act upon the receptacles 612A,612B, the filters 634A, 634B and the metal contained therein to increasemetal flow through the filters 634A, 634B and the device 610. In thealternative, one or more vibrators 624C, like vibrators 424A and 424Bmay be used to act directly on the metal M in conduit 660, 660A, 660B,etc. and receptacles 612A, 612B to improve flow through filters 634A,634B and the device 610. The filters 634A, 634B may be of the samethickness and porosity or of different thickness and or porosity. Thevibrators, e.g., 324B, 424A, 524C, 624C, etc., shown in FIGS. 1-9 may beoriented to generate vibration forces in a a selected direction, e.g.,at an orientation of 45° relative to the filter 34, 134, 234, 334A, etc.and/or the metal flow direction.

Experimental Testing Lab Scale

The apparatus and methods described above were tested under theparameters listed below in Table 1. More particularly, a filter device10 like that shown in FIGS. 1-3 with a vibrator 24 or 24′ was utilizedto filter molten aluminum using the stated parameters of Table 1.

TABLE 1 CFF Metal Temp Filter Height of used before CFF Time toVibrating Filter weight Priming Test ppi Alloy pouring C preheat primesystem weight g empty g mm 1 30 P1020 700-710 yes 30 no 1709 208 2 60P1020 700-710 yes 30 no 282 3 60 P1020 700-710 yes 15 no 2055 282 4 60P1020 700-710 yes 20 Vibco on 203 steel box 5 60 5% Mg 700-710 yes 20Vibco on 203 steel box 6 50 5% Mg 720 and more yes 20 With the 203 armand Vibco system 7 50 4.0% Mg 700-710 yes Vibco on 203 steel box 8 603.5% Mg 700-710 yes 15 no 2000 282 9 60 3.5% Mg 700-710 yes 8 Jack 452352 203 10 60 3.5% Mg 700-710 yes 35 Jack 45 127 11 50 3.5% Mg 720 andmore yes 5 Jack 45 2337 127 12 60 3.5% Mg 720 and more yes 5 Jack 452226 127 13 60 3.5% Mg 720 and more yes 15 Jack 45 76.2 14 40 3.5% Mg720 and more no 15 Jack 45 127 15 50 3.5% Mg 720 and more no 15 Jack 45127 16 60 3.5% Mg 720 and more no n/a Jack 45 127 17 50 3.5% Mg 720 andmore no 20 Jack 45 203.2 18 60 3.5% Mg 720 and more yes 12 Jack 45 152.419 50 3.5% Mg 720 and more yes 20 air vibration 152 system 20 30 2.5% Mg720 no 60 no 1594 510 127 21 30 2.5% Mg 717 yes 20 jack 45 2126 500 76.222 50 2.5% Mg 725 yes 60 no 2076 434 254 23 50 2.5% Mg 717 no 30 jack 451854 496 127 24 40 2.5% Mg 720 yes 10 jack 90 1310 530 127 25 40 2.5% Mg710 yes 20 jack vertical 1690 538 127 26 50 2.5% Mg 723 yes 30 jackvertical 1998 480 127 27 50 2.5% Mg 725 yes 15 jack 90 2190 520 127 2840 2.5% Mg 735 yes 10 jack 45 1771 498 127 29 30 2.5% Mg 722 yes 10 jackvertical 1520 488 127

As can be appreciated from the above table, there is a correlationbetween the time to prime, whether vibration is used and the deviceused. More particularly, holding other parameters equal, i.e., ppi,alloy, temperature, pre-heating of filter, etc., and varying thepresence of vibration and type of vibrator, one series of testingindicated that the time to prime 1) with no vibration was 22 seconds; 2)with vibrations from a jackhammer drill, 14 seconds; 3) with vibrationsfrom a Vibco vibrator, 20 seconds; and 4) with vibrations from anotherair vibrator, 20 seconds. This testing indicates that vibration promotesquicker priming and that the jackhammer drill was the most effectivevibrator.

As can be appreciated from Table 1, there is a correlation between theweight of the filter in grams/cm2, pre-heating of the filter and whethervibration is used. The filter is weighed after use and the weightincludes the weight of the filter itself plus any residual metal thatremains in the filter. The greater the weight, the better, the weightbeing an indication of the filter area/volume used. In a poor use offilter area, a small cross-sectional area or channel through the filterconducts the metal through the filter. More effective filtrationconditions utilize more of the filter to pass metal, leading to greaterthroughput and better filtering due to the distribution of metal flowover the entire filter. Holding other parameters equal: ppi, alloy,temperature, pre-heating of filter, etc., and varying the filterpreheating and vibration level between vibration and no vibration led tothe following results: 1) filter cold, no vibration: 1594 g/cm2; 2)filter cold, with vibration: 1854 g/cm2; 3) filter pre-heated, novibration: 1960 g/cm2. 4) filter pre-heated, vibration applied: 2162g/cm2; This testing indicates that vibration promotes betterdistribution of metal flow through the filter, either with or withoutpre-heat relative to no vibration being applied.

As can be appreciated from Table 1, there is a correlation between thetemperature of the metal, the presence of vibration and the time toprime, i.e., the greater the temperature, and the presence of vibration,the shorter the time to prime. Holding other parameters equal: ppi,alloy, etc., and varying the metal temperature and vibration levelbetween vibration and no vibration led to the following results: 1)metal temp 720 C, no vibration, time to prime: 21 seconds; 2) metal temp720 and above, no vibration, time to prime: 12 seconds; 3) metal temp710 C, filter preheat, with vibration, time to prime: 12 seconds; 4)metal temp 710 C, filter cold, with vibration, time to prime: 17seconds. This testing indicates that vibration promotes betterdistribution of metal flow through the filter, either with or withoutpre-heat relative to no vibration being applied.

Testing has revealed that there is a correlation between the weight ofthe filter when tested in g/cm2 and the location and orientation of thevibration source. More particularly, holding other parameters equal,i.e., ppi, alloy, temperature, pre-heating of filter, etc., and varyingthe orientation of the vibrator 24′ (FIG. 3) to change the angle A ofthe vibration force F between 45°, 90° and vertical (in line with or at0/180°) positions relative to metal flow, one series of tests indicatedthat the weight: 1) with vibrations from a jackhammer drill at 45° was:2111 g/cm2; 2) with vibrations from a jackhammer drill at 90°: 1750g/cm2; 3) with vibrations from a vertical jackhammer drill: 1738 g/cm2;and 4) the weight without vibrations was 1886 g/cm2. This testingindicates that vibration with the jackhammer drill was the mosteffective at an angle of 45°, with 90° and vertical orientations beingcounterproductive.

Testing has revealed that there is a correlation between the time toprime and the location and orientation of the vibration source. Moreparticularly, holding other parameters equal, i.e., ppi, alloy,temperature, pre-heating of filter, etc., and varying the orientation ofthe vibrator 24′ (FIG. 3) to change the angle of the vibration forcebetween 45°, 90° and vertical positions relative to the metal flow, andthe presence of vibration, which is varied between vibrate and novibrate, indicated that the time to prime: 1) with no vibrations was 30seconds; 2) with vibrations from a jackhammer drill at 45°: 14 seconds;3) with vibrations from a jackhammer drill at 90°: 13 seconds; and 4)with vibrations from a vertical jackhammer drill: 20 seconds. Thistesting indicates that vibration promotes quicker priming and that thejackhammer drill was the most effective at an angle between 45° and 90°.

The foregoing testing was repeated changing the ppi values of thefilters between 30 ppi and 40 ppi and weighing the filters. The testingrevealed: 1) a 30 ppi filter with no vibration resulted in a weight of1,147 g/cm2; 2) a 30 ppi filter with vibrations from a jackhammervibrator at 45° relative to the direction of metal flow resulted in aweight of 1,626 g/cm2; 3) a 30 ppi filter with vibrations from avertical jackhammer vibrator resulted in a weight of 1,032 g/cm2; 4) a40 ppi filter with vibrations from a jackhammer vibrator at 45° resultedin a weight of 1,273 g/cm2; 5) a 40 ppi filter with vibrations from ajackhammer vibrator at 90° resulted in a weight of 780 g/cm2; and 6) a40 ppi filter with vibrations from a vertical jackhammer vibratorresulted in a weight of 1152 g/cm2. The foregoing tests indicate thatthe 45° orientation worked the best for both 30 and 40 ppi filters.

The foregoing testing was extended 50 to ppi filters resulting in thefollowing results: 1) a 50 ppi filter with no vibration resulted in aweight of 1,642 g/cm2; 2) a 50 ppi filter with vibrations from ajackhammer vibrator at 45° relative to the direction of metal flowresulted in a weight of 1,837 g/cm2; 3) a 50 ppi filter with vibrationsfrom a jackhammer vibrator at 90° resulted in a weight of 1670 g/cm2; 4)a 40 ppi filter with vibrations from a vertical jackhammer vibratorresulted in a weight of 1,518 g/cm2. The foregoing tests indicate thatthe 45° orientation worked the best for the 50 ppi filter.

The testing revealed that vibration had a positive impact on metalimpregnation of the filter resulting in a 5% to 13% increase, dependingon the filter. 30 ppi and 60 ppi filters had more than a 10% increase ofmetal impregnation with vibration. This beneficial effect is enhancedwhen the filter is preheated, showing an improvement in filterimpregnation by metal of 13% for 50-60 ppi filters and a 24% increasefor a 30 ppi filter.

A consideration of vibration vs. no vibration for a variety of filtersizes, all other factors the same, led to the following resulting filterweights: 1) 30 ppi, no vibration: 1651 g; 2) 30 ppi, with vibration:1823 g; 3) 50 ppi, no vibration: 2076 g; 4) 50 ppi, with vibration: 2175g; 5) 60 ppi, no vibration: 2027 g; and 6) 60 ppi, with vibration: 2289g.

A consideration of vibration force orientation for a variety of filtersizes, all other factors the same, led to the following resulting filterweights: 1) 30 ppi, no vibration: 1709 g; 2) 30 ppi, with vibrationusing jack hammer drill at 45° relative to the direction of metal flow:2126 g; 3) 50 ppi, no vibration: 2076 g; 4) 50 ppi, with vibration usingjack hammer drill at 45°: 2337 g; 5) 60 ppi, no vibration: 2027 g; and6) 60 ppi, with vibration using jack hammer drill at 45°: 2289 g.

A beneficial effect on time to prime was also observed with vibration ofthe filter. More particularly, a preheated 30 ppi filter time-to-primewithout vibration was 30 seconds, with vibration, 15 seconds. Apreheated 40 ppi filter took 13 seconds to prime with vibration. Apreheated 50 ppi filter time to prime without vibration was 60 seconds,with vibration, 18 seconds. A preheated 60 ppi filter time to primewithout vibration was 20 seconds, with vibration, 16 seconds. In eachcase, filter impregnation and time to prime were improved by vibration.For a given filter, (preheated, 30 ppi) the time to prime was 30seconds, the same filter showed times to prime of 14 seconds whenvibrated by a jackhammer drill at 45° relative to metal flow°, 13seconds at 90° relative to metal flow and 20 seconds when at a verticalorientation, i.e. in the same direction as metal flow.

The cast alloys were also tested to determine the metal cleanliness withLiMCA (Liquid Metal Cleanliness Analyzer) and PoDFA (Porous Disk FilterAnalysis from ABB Group new.abb.com and it was determined that thevibration assist in filtering did not disturb metal cleanliness, eventhough other parameters, such as time to prime, resultant filter weight,the ability to use finer filters and the removal of more inclusions wereimproved.

Full Scale Testing

Full scale testing was conducted at a casting facility that producedingots of C17N, a pure alloy (1050 type) that is used, e.g., in lithoapplications, C42Z (5042) which contains 3.5% Mg and C52Z (5352), whichcontains 2.5% Mg. C52Z and C42Z may be used for can body applications.The cast alloys were tested to determine the metal cleanliness withLiMCA and PoDFA.

A minimum of two castings were produced per alloy to produce ingots 330inches (minimum) in length. A maximum of three ingots could be casted ata time, which is consistent with the maximum flow rate specified(333-417 Kg/min) by the filter supplier for a 60 or 70 ppi filter thatis 23×23 inches. Only 60 ppi and 70 ppi filters were used. LiMCAmeasurements were done on four castings. PoDFA were taken before andafter a double CFF filter at 2000 mm and 4000 mm of the cast. LiMCa wastaken continuously during the cast after the CFF with a special tube tominimize the effect of chlorides and bubbles at the furnace exit.Vibration of the filter was started prior to the molten metalencountering the filter and was stopped prior to casting 50 mm of theingot. A temperature differential of about 100° C. between the bottom ofthe filter and top of the filter aids in filtration. Heating of thefilter was done with a gas burner below and on top of the filter. Alaser was used at the furnace exit after the filter to determine themetal head lost during casting. A pneumatic piston vibrator, viz., aMartin P-Series P4S vibrator from Martin Engineering of Neponset, Ill.,www.martin-eng.com, was utilized as the vibrator. The vibration systemwas operated at 60-80 psi, producing about 1825 impacts per minute at aforce of 2,105 lbs. per impact. The molten alloys were subjected to TAC(treatment of aluminum in crucible) to remove Na and Ca and alkalies.Filter weights were recorded.

The amount of time the vibrator was operated was varied to compensatefor filter temperature variations to avoid casting abort due to filterclogging before 50 mm of ingot was cast. The vibration force was rampedduring the starting process to cover all optimal directional G forces.Forces and corresponding pressures that resulted in resonance of thefilter assembly were avoided. Resonance was observed at 30-40 psi. Inthis testing, maximum priming was achieved at 70 psi of air pressure tothe vibrator.

The results of the full scale testing showed comparable results as inthe laboratory scale testing, with an increase of 18% more metal in thefilter for 60 and 70 ppi filters as a result of applying vibrations inaccordance with the present disclosure. For example, standard castingprocesses without vibration yielded an average of 57.75 g/cm2. Uponapplication of vibration, the filters showed and average of 68.08 g/cm2weight, corresponding to an 18% increase in weight. A comparison oftotal weights of preheated filters showed the following: 1) 30 ppi withno vibration: 1709 g; 2) 30 ppi with vibration, vibrator at 45°: 2126 g;3) 50 ppi with no vibration: 2076 g; 4) 50 ppi with vibration, vibratorat 45°: 2337 g; 5) 60 ppi with no vibration: 2027 g; 6) 60 ppi withvibration, vibrator at 45°: 2289 g.

The foregoing vibratory techniques and apparatus have been explainedindependently, but each and all could be employed in combination. Thatis, more than one type of vibrator 24 may be utilized on a singlefiltering device 10 and may be operated simultaneously or in a sequence.In accordance with the present disclosure, a vibrator like, e.g.,vibrators 24, 124A, may be retrofitted to an existing conduit orreceptacle to improve filtration by a ceramic filter. It will beunderstood that the embodiments described herein are merely exemplaryand that a person skilled in the art may make many variations andmodifications without departing from the spirit and scope of the claimedsubject matter. For example, while the embodiments described above haverelated to the filtering of aluminum and its alloys, other metals andalloys could be amenable to filtration using the teachings of thepresent disclosure, such as die casting or iron casting. While a CCFceramic filter is described above as the filtering medium, other typesof filters could be employed in executing the apparatus and methoddisclosed in the present application, such as, bed filtration or poroustube filtration. While the vibrators described above may be used toproduce a continuous vibration over a given period, a vibrator may alsobe employed to produce a single shock, generating a shock wave throughat least one of the molten metal, the receptacle or the filter. All suchvariations and modifications are intended to be included within thescope of the present disclosure.

We claim:
 1. A filter device, comprising: a receptacle for molten metal,the receptacle having an inlet through which the metal may enter thereceptacle and an outlet through which the metal may exit thereceptacle; a filter element within the receptacle positioned betweenthe inlet and the outlet, the filter capable of passing molten metalthere through; and a vibrator capable of inducing vibrations in themetal.
 2. The device of claim 1, wherein the vibrator contacts a surfaceof the receptacle.
 3. The device of claim 1, wherein the vibrator has adriven element that contacts the metal.
 4. The device of claim 3,wherein the driven element is immersed in the metal.
 5. The device ofclaim 4, wherein the device has an arm extending between the vibratorand the driven element, and wherein the arm is L-shaped.
 6. The deviceof claim 5, further comprising a support for the receptacle and whereinthe arm is attached to the support.
 7. The device of claim 6, furthercomprising at least one resilient element interposed between the arm andthe support enabling the arm to vibrate under the influence of thevibrator at least partially independently of the support.
 8. The deviceof claim 1, wherein the vibrator is at least one of electrically,pneumatically or hydraulically driven.
 9. The device of claim 1, whereinthe vibrator generates a force with a direction between 45° and 90°relative to the direction of metal flow.
 10. The device of claim 1,wherein the vibrator is mounted on an exterior surface of the receptacleproximate the filter element.
 11. The device of claim 1, furthercomprising a controller for the vibrator, the controller capable ofadjusting the vibrator in at least one of frequency and amplitude. 12.The device of claim 1, wherein the receptacle has an inner liner thatreceives the metal and an outer shell.
 13. The device of claim 12,further comprising at least one resilient member interposed between theinner liner and the outer shell.
 14. The device of claim 13, wherein theat least one resilient member at least partially isolates the vibrationof the inner liner from the shell.
 15. The device of claim 1, whereinthe filter is a ceramic foam filter.
 16. The device of claim 15, whereinthe filter has >50 pores per inch.
 17. The device of claim 15, whereinthe filter has ≥60 pores per inch.
 18. The device of claim 1, whereinthe molten metal includes aluminum.
 19. The device of claim 3, whereinthe driven element is at least partially covered by a refractorymaterial.
 20. The device of claim 1, further comprising at least oneadditional vibrator, the vibrator and additional vibrator operableindependently or simultaneously and at the same frequency or differentfrequencies.